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0ee9b2e446
So far the INIT segment was run from the later heap+stack. Now the INIT segment is run from the later BSS. The background is that so far the INIT segment was pretty small (from $80 to $180 bytes). But upcoming changes will increase the INIT segment in certain scenarios up to ~ $1000 bytes. So programs with very limited heap+stack might just not been able to move the INIT segment to its run location. But moving the INIT segment to the later BSS allows it to occupy the later BSS+heap+stack. In order to allow that the constructors are _NOT_ allowed anymore to access the BSS. Rather they must use the DATA segment or the new INITBSS segment. The latter isn't cleared at any point so the constructors may use it to expose values to the main program. However they must make sure to always write the values as they are not pre-initialized.
139 lines
4.1 KiB
ArmAsm
139 lines
4.1 KiB
ArmAsm
; mainargs.s
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;
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; Ullrich von Bassewitz, 2003-03-07
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; Based on code from Stefan A. Haubenthal, <polluks@web.de>
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; 2003-05-18, Greg King
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; 2004-04-28, 2005-02-26, Ullrich von Bassewitz
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;
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; Scan a group of arguments that are in BASIC's input-buffer.
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; Build an array that points to the beginning of each argument.
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; Send, to main(), that array and the count of the arguments.
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;
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; Command-lines look like these lines:
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;
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; run
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; run : rem
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; run:rem arg1 " arg 2 is quoted " arg3 "" arg5
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;
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; "run" and "rem" are entokenned; the args. are not. Leading and trailing
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; spaces outside of quotes are ignored.
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;
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; TO-DO:
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; - The "file-name" might be a path-name; don't copy the directory-components.
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; - Add a control-character quoting mechanism.
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.constructor initmainargs, 24
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.import __argc, __argv
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.include "plus4.inc"
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MAXARGS = 10 ; Maximum number of arguments allowed
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REM = $8f ; BASIC token-code
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NAME_LEN = 16 ; Maximum length of command-name
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; Get possible command-line arguments. Goes into the special INIT segment,
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; which may be reused after the startup code is run
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.segment "INIT"
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initmainargs:
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; Assume that the program was loaded, a moment ago, by the traditional LOAD
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; statement. Save the "most-recent filename" as argument #0.
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lda #0 ; The terminating NUL character
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ldy FNAM_LEN
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cpy #NAME_LEN + 1
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bcc L1
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ldy #NAME_LEN ; Limit the length
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bne L1 ; Branch always
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L0: lda #FNAM ; Vector address
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jsr FETCH ; Load byte from RAM
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L1: sta name,y
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dey
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bpl L0
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inc __argc ; argc always is equal to, at least, 1
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; Find the "rem" token.
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ldx #0
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L2: lda BASIC_BUF,x
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beq done ; No "rem," no args.
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inx
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cmp #REM
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bne L2
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ldy #1 * 2
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; Find the next argument
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next: lda BASIC_BUF,x
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beq done ; End of line reached
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inx
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cmp #' ' ; Skip leading spaces
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beq next
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; Found start of next argument. We've incremented the pointer in X already, so
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; it points to the second character of the argument. This is useful since we
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; will check now for a quoted argument, in which case we will have to skip this
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; first character.
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found: cmp #'"' ; Is the argument quoted?
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beq setterm ; Jump if so
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dex ; Reset pointer to first argument character
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lda #' ' ; A space ends the argument
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setterm:sta term ; Set end of argument marker
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; Now store a pointer to the argument into the next slot. Since the BASIC
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; input buffer is located at the start of a RAM page, no calculations are
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; necessary.
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txa ; Get low byte
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sta argv,y ; argv[y]= &arg
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iny
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lda #>BASIC_BUF
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sta argv,y
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iny
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inc __argc ; Found another arg
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; Search for the end of the argument
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argloop:lda BASIC_BUF,x
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beq done
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inx
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cmp term
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bne argloop
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; We've found the end of the argument. X points one character behind it, and
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; A contains the terminating character. To make the argument a valid C string,
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; replace the terminating character by a zero.
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lda #0
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sta BASIC_BUF-1,x
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; Check if the maximum number of command line arguments is reached. If not,
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; parse the next one.
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lda __argc ; Get low byte of argument count
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cmp #MAXARGS ; Maximum number of arguments reached?
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bcc next ; Parse next one if not
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; (The last vector in argv[] already is NULL.)
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done: lda #<argv
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ldx #>argv
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sta __argv
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stx __argv + 1
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rts
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.segment "INITBSS"
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term: .res 1
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name: .res NAME_LEN + 1
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.data
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; char* argv[MAXARGS+1]={name};
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argv: .addr name
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.res MAXARGS * 2
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